Gonorrhoeae is a most persistant pandemic affliction of the human race. In the United States alone, approximately 4 million persons annually appear in clinics and physicians offices with this sexually transmitted disease. These individuals, so experience has shown, form a hard core source of new infections for additional individuals, and are, themselves, consistently becoming reinfected. There is a significant and growing need for a vaccine to contain this contagion.
Despite this urgent demand, no successful vaccine has yet become available. One of the principal problems which has impeded the production of a vaccine is the antigenic heterogeneity of the N.g. microorganisms. Another is the complex nature of the microorganisms. It has been repeatedly observed that the N.g. strain responsible for an epidemic in one community has a substantially different antigenic profile from the strain which is the source of infection in another community. As a result, the development of a vaccine effective against the former strain will not guarantee success against the latter strain. The problem then becomes one of discovering and isolating an antigen which is common to all strains and capable of eliciting an antibody response at a level which will afford protection against infection or reinfection. Alternatively, the problem could be dealt with by the discovery and isolation of an antigen which, while not necessarily common to all N.g. microorganisms, is capable of eliciting a protective antibody response against all of them. A more realistic and practical goal would be to discover and isolate a small number of antigens which could be combined in one vaccine to stimulate immunity from infection from most, if not all, N.g. microorganisms.
As indicated above, the problem of isolating useful antigens is further complicated by the complexity of the cellular structure of the N.g. microorganisms. Antigens are present in the pili, principal outer membrane, and lipopolysaccharides (LPS) in the cell. To separate these antigens in a useful form, free of contamination by other materials and by each other, is indeed a challenge. Moreover, some of the contaminants are toxic. LPS contaminants in isolates which might be considered potentially useful for vaccines have been observed to cause fever, shock and death in experimental animals. In humans, they would be expected to cause severe pain and swelling at the site of infection, severely elevated temperature, chills and perspiration.
Since antigens are proteins, it is necessary to utilize an isolation procedure which does not denature and thereby inactivate the protein. Moreover, it is necessary that the antigen isolated be immunogenic. To be useful as a vaccine, it is not sufficient that the antigen merely conjugate with existing antibodies. It must stimulate the host to produce a strong and persistant antibody response.